$145.00

RGB kit 650-150 / 532-80 / 450-120 TTL with optics 12VDC[AIX-RGK-350]

by Terry Lyon

AXIZ LLC RGB Kit 650-150 / 532-80 / 450-120 TTL with Optics 12VDC

DISCLAIMER. The author of this “customer comment” assumes no responsibility for the unsafe use of this laser kit and the following assembly and use information is intended to help prevent potentially harmful eye exposures. The visible and invisible laser beams emitted by this kit must be terminated in a backstop that is within a controlled area to prevent human access. Further review of current laser safety standards is advised. This author has volunteered to create these comments without any financial compensation and they need to be used with caution.

This RGB kit exceeded my expectations considering the low cost, small size, light weight (less than ½ pound) and it even contained sophisticated optics to combine the three beams into what appeared as white light. I remember 50 years ago when multi-wavelength lasers were a thousand times more expensive and larger in size. Back then, no federal standards and only a couple safety standards existed. Many safety standards exist today for manufacturers and users. I installed my RGB kit into an opaque enclosure to largely block extraneous radiation (secondary beams and near-infrared laser pump emissions).

The kit arrived without any connection instructions, safety instructions, or schematic/layout. It contained a laser module connected to a controller module and four sets of wires with connectors. The controller module was insulated from the mounting holes with a plastic frame so it could be mounted in a conductive aluminum enclosure. Four basic connections were made between each loose wire set connector to the blue, red, green, and white sockets along one end of the controller module. Power was connected through that white socket with red as positive 12 VDC (which should be controlled with an ON-OFF SPST switch) and black as ground. The other three wire sets are used to disable individual lasers (TTL lines) so they could be connected to three individual SPST switches. Miniature toggle switches work well. When a TTL line was open, there is about 2 VDC present, and when closed each line drew about 0.5 mA which turns off one diode laser. Keep these lines separated electrically from each other as when they are combined some undesirable operation can occur.

I used a 7812 (RS 276-1771) 12VDC positive voltage regulator fed from an unregulated power adapter that was rated for 1A. The RGB kit should also work OK with a regulated 12 VDC adapter or a 12VDC battery. I inserted a 1 ohm 1% resistor between the adapter and a 1000 microF filter capacitor ahead of the 7812 regulator input to ground and a 0.1 microF capacitor on the regulated output line. Voltage developed across the resistor can be used to determine the operating current. The 7812 was bolted to an aluminum enclosure which was a box approximately 2 x 3 x 5 inch (RS 270-0238). This enclosure required some trimming of the controller module plastic mounts to fit in the enclosure. It is really important to enclose the laser module in an opaque box with a single aperture to transmit the combined beams as this will block many other potentially harmful laser beams. Also, I would recommend against using a black plastic enclosure as many transmit invisible NIR radiation from the 800 nm and 1064 nm laser beams that are often present in the 532 nm output of green laser diodes. I found that the aluminum enclosure was adequate for cooling the laser module and the 7812 for non-continuous operation, dissipating about 7-8 watts for a few minutes. Continuous operation may require a heat sink with a fan for which there appears to be a separate connection on the controller module.

The following list contains some measured results for my completed “AXIZ LLC RGB kit 650-150 / 532-80 / 450-120 TTL with optics 12VDC.” Radiant power was when operated in continuous wave (CW) mode and were measured at the output where the beams were combined. Data below are listed by operating mode, peak wavelength (nm), applied voltage VDC (volts), operating current (mA), and radiant output power (mW) in the main beam:

Some other comments follow: The kit weighted about 193 gram or 6.8 oz. Peak wavelength measurements were made with an ILT950 spectroradiometer, voltage measurements were made with a Fluke 87 DMM, and radiant power measurements were made with a Scientech disk calorimeter and a calibrated Thorlabs photodiode. The output beam may have had some slight clipping at the laser exit aperture. Many green laser diodes contain a NIR pump laser (such as 808 nm) and are frequency doubled to 532 nm from a 1064 nm Nd:YAG laser. Two NIR wavelengths leaked into the output beam but were largely reduced by the beam combining optics.

This laser had a hazard category of ANSI Class 3b which can result in an immediate and permanent eye injury from momentary viewing from within the beam (intrabeam viewing) or a specular reflection of the beam. Reflections from diffuse surfaces at this class are not considered to exceed safety limits. Also, skin exposure is not considered harmful. Laser safety eye wear is advised and I added a permanent 2 x 2 filter holder at the laser exit aperture so that I could use a removable neutral density filter to reduce the output power when full power was not needed. I also added a ping-pong ball diffuser to a 2 x 2 metal plate with a hole that can be placed into the laser beam for laser demonstrations. This combination double diffused the beam with 2 ping-pong surfaces to further reduce the laser output and is considered safe for any viewing condition. I also added warning labels to the laser housing to show where the laser exit aperture was and a laser DANGER label.

My analysis was an abbreviated safety study but it did provide some estimated optical densities for safety filters that are listed below. These are the approximate optical densities for an attenuating filter to reduce the laser output to below ACGIH intrabeam laser “point-source” viewing safety exposure limits. Viewing through such filters would still be very bright and not advised. Data below are listed by operating mode, peak wavelength (nm), and optical density (OD) for ACGIH to 8 hours:

Some other comments follow: Greater NIR levels existed within the extraneous beams created by the combining optics and these must be blocked with an opaque enclosure or barrier such as a flat-black painted metal surface.